An upright shoulder decreases the length of stride and can be a really uncomfortable, rough ride. The legs take a beating, too, and depending on the rest of his conformation, a horse with an very steep shoulder could have soundness issues down the road. ( no pun intended )

This little horse looks uncomfortable to me, both standing and moving...not sure I can put my finger on why exactly I get that impression. His legs are light and feet are small; in combination with that shoulder I'm not sure he's the best candidate for staying sound over the long term. jmo